MICROBIAL HYDROCARBON DEGRADATION WITHIN SEDIMENT 

 IMPACTED BY THE AMOCO CADIZ OIL SPILL 



by 



Ronald M. Atlas 

 Department of Biology 

 University of Louisville 

 Louisville, Kentucky 40292 



INTRODUCTION 



The wreck of the AMOCO CADIZ in March 1978 released over 210,000 

 tons of oil into the marine environment. As much as one third of the 

 spilt oil may have been washed into the intertidal zone. The spill 

 occurred during storm surges, thereby spreading the oil throughout the 

 intertidal zone. Two years after the AMOCO spill, the wreck of the 

 tanker TANIO resulted in another oil spill that contaminated much of the 

 same Brittany shoreline impacted by the AMOCO CADIZ. This study was 

 undertaken to determine the fate of petroleum hydrocarbons within 

 surface sediments along the Brittany coast with reference to the role of 

 microorganisms in the oil weathering process. 



METHODS 



Sampling Regime 



Duplicate samples were collected at intertidal sites along the 

 Brittany coast which had received varying degrees of oiling from the 

 AMOCO CADIZ spillage (Fig. 1). The sampling sites included the salt 

 marsh at lie Grande, a beach near Portsall in the vicinity of the wreck 

 site, a mudflat in Aber Wrac'h, a beach at St-Michel-en-Greve near where 

 a large bivalve kill had been reported, a relatively lightly oiled 

 reference site at Trez Hir and a site at Tregastel which was not oiled 

 by the AMOCO CADIZ spill, but was later oiled by the spill from the 

 tanker TANIO (Table 1). Surface sediment samples (upper 5 cm) were 

 collected with a 3 cm diameter soil corer. 



Samples were placed in metal cans for hydrocarbon analyses and in 

 Whirlpak bags for microbial analyses. Samples were collected during 

 December, 1978; March, 1979; August, 1979, November, 1979, March 1980, 

 July, 1980 and June, 1981; 9, 12, 17, 20, 24, 28 and 39 months after the 

 spillage, respectively. During November, 1979 sediment samples were 

 also collected at four offshore sites in the Bay of Morlaix. 



Samples for microbiological analyses were processed within four 

 hours of collection. For hydrocarbon analyses, samples were frozen and 

 shipped to Energy Resources Company (ERCO) for extraction and analysis 



